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The effects of noradrenaline and cold acclimation on isolated perfused rat heart
Vol . 8, Part 1, pp . 239-245, 1969 . Life Sciences Printed in Great Britain.
Pergamon Press
THE EFFECTS OF NORADRENALINE AND COLD ACCLIMATION ON ISOLATED PERFUSED RAT HEART N .W . Noxell and D .C . White* Department of Zoology, University of Hull, England
(Received 30 September 1968 ; in final form 2 December 1968) It has been shown (1) that xhen isolated perfused .rat hearts are repeatedly cooled and rexarmed an acclimation effect occurs resulting in a significant difference between the Heart Rate/Temperature curves for the first and second (but not subsequent) coolinga .
The Heart Pate during the second cooling xas
found to be higher at all temperatures than during the first cooling .
A
further finding xas that a loxer temperature was required to produce cardiac arrest during the second cooling than during the first cooling . Noradrenaline has been closely implicated in the process of cold acclimation (2) .
On the isolated heart it has an accelerating action sad in
almost all respects its actions oppose the effects of cooling on cardiac function . The experiments reported here were carried out to discover if the effects of cold acclimation and of noradrenaline could be distinguished in the isolated heart during cooling .
The combined effects of the txo agents
was also observed . Materials and P?ethods A Langendorf perfusion. apparatus modified from that of Bleehan and Fisher (3) was used .
The heart xas perfused at a pressure of 80cm of rater
and the perfusion system and heart chamber were enclosed in a eater jacket by means of which the temperature of the preparation xss controlled . The nerfusate u sed ras a modified Krebs-Henseleit solution containing * Present address : Department of Anaesthesia, Roysl Infirmary, Aberdeen, Scotland .
239
~OLATED PERFUSED HEART
240
Vol . 8, No . 5
dsztroae, heparin and phenol red (4) .
This ran gained rich 59~+C02 is
o~gea until the colour vas constant .
Oaeeing xas contimied is the reservoir
of the appaatus .
The pH of the pertusate after gassing rsa 7 .3 .
To avoid coataaination of the perluaate and changes in dsvg oonoeatratioa reoiroulatioa of psrtaeate ras act eaployed ;
after one parings through the
heart it xas discarded . !stale Yistar albino rats xsighing 250-350 ga xsre aced .
They rare
sept in an aman! house at 21 °C cad fed on coaaercial rst cake and rater ad libitua.
hah rat ras anaesthetised rich ether and heparinissd rith 50 unite of heparin adainistered via the jugular vein .
Oae aimite later the heart xas
moved and transferred to a dish of o~genated perfusate rhile a polythene o.* ~ ia xas tied into the aorta.
The ca *~ i . ran attached to a small
reservoir of o~genated perfusate ao that psrluaion began as soon ae the oaaaula ras is position.
after rashiag free of blood the heart ras detaohsd
Eton the rasping apparatus and txsnefsrred to the heart cbaaber There psrtueioa ras oontimied. The prepaatioa rsa stabilised at 25°C cad rhea the beats beoaae regular cad of constant rate cooling tae began.
Cooling vas carried out at the esaa
rate is all ezpsriaeata cad avsreged 0 .4oC per aim~.te . During cooling the heart rats ras timed over periods of 30 seoe at interval rhioh varied betrsen 2 sins at the beginning of cooling cad 1 ain as cardiac arrest approached .
It a~ dissociation of atria! cad ventricular
bead ooonrred at for t~psraturea the ventricular rate ras recorded . rhioh did cot beat regularly during cooling rere diaoarded .
Hearts
Cardiac arrest
ru recorded rhea no ventricular beat ran seen during a period of 20 seos . Teapintnres rare recorded by a theraoaster aonated close to the heart,
LSOLATED PERFUSED HEART
Vol . 8, No . 5
241
previous ezperiments having shorn that the perfhsate temperature xas the acme as that of the chamber. After cardiac arrest had occurred the apparatus xas rapidly rexarmed sad the preparation restabilieed at 25 oC before the second cooling xaa carried out is a manner identical to the first .
In acme ezperimente a third and a
fourth cooling xere carried out . Yhsn noradrenalias xaa added the concentration in the perfusate xaa 1 pg/ml and the preparation used xaa noradrenaline acid tartrate (Levophed, Bayer Products) . Pzperimeata and Results (1)
Effeota of cooling for the first time xith and xithout aoradrenaline. 26 hearts xere cooled xithout noradrenaline in the pertueate, and the
mean curve produced by plotting contraction rate against temperature is shorn as Curve A Fig, 1 .
Cardiac arrest occurred at a mean temperature of 13 .3°C
(3 .E . ± 0.22) . Four hearts were cooled for the first time xith noradrenaliae and the curve of Rate/Temperature is ehoxn ea Curve C in Fig. 1 . occurred at a mean temperature of 10 .3° C (± ,23) .
Cardiac arrest
This is significantly
lower than the mean temperature of cardiac arrest in the hearts cooled xithout noradrenaline .
The deviation from the mean in thin group of hearts vas eo
small that it xas not necessary to perform more than four ezperimenta in this getup . (2)
Effects of repeated cooling without noradrenaline (Acclimation) . 5 hearts xere cooled to arrest for a second time and the mean
Rate/Temperature curve for this second cooling is ehoxn as Curve B.
This
curve is of significantly smaller elope than that of the first oooling (Curve A) and the cardiac arrest temperature ie significantly lower in the second cooling . (1) .
This demonstrates the acclimation effect previously reported
No significant differences xere found betxsen second and subsequent
ISOLATED PERFUSED HEART
242
100 90
Vol . 8, No . 5
BEATS PER MINUTE
BO 70 60 SO 40 30 20 )0 CA
.i.C
10
5
1
1~5
2~0
TEMPERATURE- °C
Mesa Heart Hate/Tupex~aturs Currea . ~ . - Hrst cooling, rithout noradrenaline . H . - Ssoond cooling, rithout not+aàrenaline : C . - Hrst cooling, rith noradrsnalins . D . - Third cooling, first and second rithout aoradrenaline third rith aoradrsaaline . C .l. - äsan cardiac arrest terpsnturs . oooliage . (3)
Sifecta of aooliaation and no :adreaalins ooabiaed . The fire hearts rhich had been aooliaated (in (2) abo~s) rere subjected
to a third ooôling and for this third cooling noradrenaline rae added to the perfnsate .
The lean Eate/Temperature cure is shorn as Curs D lig . 1 .
It can
Vol . 8, No . 5
1SaLATED PERFUSED HEART
24 3
bs seen that Cures D (noradrenaline with aoolirtioa) dose not differ iron o Curve C (aoradrenalins without accusation) between 20 and 14 C but below 14°C Cures D develops a sigoifioantly caller slope (P < 0.001) and also the cardiac arrest tesperature for Curve D ie significantly lover than that of Curve C .
The figures being 5.66°C (± 0.49) for Cures D and 10 .3 °C (± 0.23)
for Curve C .
Ths above resnlte shoe that the addition of noradrenaline to the psrfueate incxroased the heart rate throughout the cooling process.
llthough the Bate
Tenpsrature curve vas sowed to the left there vas no difference in slope between the control group (Ourve ~) and the noradrsnaline group.
The addition
of noradrsnaliae also resulted is the hearts continuing to beat to a tespsrature three degrees lover than the controls . These results are xhat night be ezpected fros a consideration of the actions of catscholaainss oa cardiac tissues .
(The actions of adrenaline and
noradrenaline oa the isolated heart are indietinguiehable although there are species differences is relative potency) .
Ia alsoet all respects the actions
of catecholaaiaea oppose the changes produced is cardiac f~aotion by cooling. Catecholaainea increase the rate of ispulee formation in the cardiac pacenaksr and all cardiac tissues capable of autosaticity (5) .
They also increase
the speed of iapulas conduction through all the cardiac tissues particularly the ~-V node (6) .
Catecholaaiase also increase the rates of contraction and
relazation of cardiac suacle (7) . The basic sechaaisms by rhich a tissue becomes acclimated to cold ere not understood but is the experiments described hers the process shoved itself ae a shift in the Bate~Tenperature sores to the left and a lowering of the teapsrature at xhich cardiac sweat occurred .
The reduction in cardiac
arrest tsapsrature produced by acclimation wan not significantly different to that produces by noradrenalias .
Vol . 8, No . 5
ISOLATED PERFUSED HEART
244
Hoxever, unlike the noradrenaline effect, the shlft to the left is the Rate/Temperature curve of the ncclimnted hearts xas accovpanied by a change of slops. fihen considering the role of catecholamines is cold aocllmation various sechaaisme have been proposed (8) .
Ths szperirents reported here suggest
that the process of cold acolimation produces a change in sensitivity of the heart to noradrsnaline as revealed by Curve D belox 14 o C .
Hoxsver,
noradrenaline does sot cause a change in slops of the Rate/Temperature curve xhsrsas acclimation doss .
The change is slope of Curve D belox 14oC suggests
that it might be amore correct to regard acclimation as a separate process xhich occurs both xith and xithout noradrsnaline. Conolnsions Noradrenaliae increases the rate of beating of the isolated heart at any given teaparature sad also causes a reduction of the teaperature at xhich aardiao arrest occurs .
It does not alter the elope of the Heart Rats/
Tsrpenturs curve. ~oolLation is a separate process xhioh increases the heart rate at lox t~peraturee during second and subsequent cooliage .
It decreases the elope
of the Heart Rate/Te~psrature curve significantly, and operates in both aoradrsnalias psrfused and control hearts . 8eferencee 1. 2.
N.Y . NOÜELL and D.C . fiHITS, Nature ~Londoa) 2~ 913 (1967) . 3.lI. HOEY~TH aad C .D . HOTiELL, ~dantation to the Snvimamsat . ed . ~.B . M11 p. 153 .
V. Pbysiol. 8oc. Washington D .C . (1964) .
3,
If .1[. BL~+w aad B.B . 1rI3HSH, ~. Phvsiol . 1~, fi30 (1954) .
4.
L1I, T~YLOH, Gf .D . HIIF1rINS$ and D .T . YOIING, J. ~DDl . Phvsiol. ~6, 95 (1961) .
Vol. 8, No. 5
LSOLATED PERFUSED HEART
Btfaraneaa
(coat .)
5.
s . CCR~80Er and 9 . if$IDltl~, H.1~. Ph~siol . ants . ~, ~j2 (1950 .
6.
H .H, SY,f,Ië and C .L . YHIHi>d$, J . Pbaraaaoi , 120, 137 (1957) .
7.
L .I . OOLDH>I80, ~a. J . Ph~aiol . ~, 92 (1958) .
8.
J . LEWC, ~ota ~aiol . 8oaad . ~, 8oPP1 " 183 (1961) .
245
Pergamon Press
THE EFFECTS OF NORADRENALINE AND COLD ACCLIMATION ON ISOLATED PERFUSED RAT HEART N .W . Noxell and D .C . White* Department of Zoology, University of Hull, England
(Received 30 September 1968 ; in final form 2 December 1968) It has been shown (1) that xhen isolated perfused .rat hearts are repeatedly cooled and rexarmed an acclimation effect occurs resulting in a significant difference between the Heart Rate/Temperature curves for the first and second (but not subsequent) coolinga .
The Heart Pate during the second cooling xas
found to be higher at all temperatures than during the first cooling .
A
further finding xas that a loxer temperature was required to produce cardiac arrest during the second cooling than during the first cooling . Noradrenaline has been closely implicated in the process of cold acclimation (2) .
On the isolated heart it has an accelerating action sad in
almost all respects its actions oppose the effects of cooling on cardiac function . The experiments reported here were carried out to discover if the effects of cold acclimation and of noradrenaline could be distinguished in the isolated heart during cooling .
The combined effects of the txo agents
was also observed . Materials and P?ethods A Langendorf perfusion. apparatus modified from that of Bleehan and Fisher (3) was used .
The heart xas perfused at a pressure of 80cm of rater
and the perfusion system and heart chamber were enclosed in a eater jacket by means of which the temperature of the preparation xss controlled . The nerfusate u sed ras a modified Krebs-Henseleit solution containing * Present address : Department of Anaesthesia, Roysl Infirmary, Aberdeen, Scotland .
239
~OLATED PERFUSED HEART
240
Vol . 8, No . 5
dsztroae, heparin and phenol red (4) .
This ran gained rich 59~+C02 is
o~gea until the colour vas constant .
Oaeeing xas contimied is the reservoir
of the appaatus .
The pH of the pertusate after gassing rsa 7 .3 .
To avoid coataaination of the perluaate and changes in dsvg oonoeatratioa reoiroulatioa of psrtaeate ras act eaployed ;
after one parings through the
heart it xas discarded . !stale Yistar albino rats xsighing 250-350 ga xsre aced .
They rare
sept in an aman! house at 21 °C cad fed on coaaercial rst cake and rater ad libitua.
hah rat ras anaesthetised rich ether and heparinissd rith 50 unite of heparin adainistered via the jugular vein .
Oae aimite later the heart xas
moved and transferred to a dish of o~genated perfusate rhile a polythene o.* ~ ia xas tied into the aorta.
The ca *~ i . ran attached to a small
reservoir of o~genated perfusate ao that psrluaion began as soon ae the oaaaula ras is position.
after rashiag free of blood the heart ras detaohsd
Eton the rasping apparatus and txsnefsrred to the heart cbaaber There psrtueioa ras oontimied. The prepaatioa rsa stabilised at 25°C cad rhea the beats beoaae regular cad of constant rate cooling tae began.
Cooling vas carried out at the esaa
rate is all ezpsriaeata cad avsreged 0 .4oC per aim~.te . During cooling the heart rats ras timed over periods of 30 seoe at interval rhioh varied betrsen 2 sins at the beginning of cooling cad 1 ain as cardiac arrest approached .
It a~ dissociation of atria! cad ventricular
bead ooonrred at for t~psraturea the ventricular rate ras recorded . rhioh did cot beat regularly during cooling rere diaoarded .
Hearts
Cardiac arrest
ru recorded rhea no ventricular beat ran seen during a period of 20 seos . Teapintnres rare recorded by a theraoaster aonated close to the heart,
LSOLATED PERFUSED HEART
Vol . 8, No . 5
241
previous ezperiments having shorn that the perfhsate temperature xas the acme as that of the chamber. After cardiac arrest had occurred the apparatus xas rapidly rexarmed sad the preparation restabilieed at 25 oC before the second cooling xaa carried out is a manner identical to the first .
In acme ezperimente a third and a
fourth cooling xere carried out . Yhsn noradrenalias xaa added the concentration in the perfusate xaa 1 pg/ml and the preparation used xaa noradrenaline acid tartrate (Levophed, Bayer Products) . Pzperimeata and Results (1)
Effeota of cooling for the first time xith and xithout aoradrenaline. 26 hearts xere cooled xithout noradrenaline in the pertueate, and the
mean curve produced by plotting contraction rate against temperature is shorn as Curve A Fig, 1 .
Cardiac arrest occurred at a mean temperature of 13 .3°C
(3 .E . ± 0.22) . Four hearts were cooled for the first time xith noradrenaliae and the curve of Rate/Temperature is ehoxn ea Curve C in Fig. 1 . occurred at a mean temperature of 10 .3° C (± ,23) .
Cardiac arrest
This is significantly
lower than the mean temperature of cardiac arrest in the hearts cooled xithout noradrenaline .
The deviation from the mean in thin group of hearts vas eo
small that it xas not necessary to perform more than four ezperimenta in this getup . (2)
Effects of repeated cooling without noradrenaline (Acclimation) . 5 hearts xere cooled to arrest for a second time and the mean
Rate/Temperature curve for this second cooling is ehoxn as Curve B.
This
curve is of significantly smaller elope than that of the first oooling (Curve A) and the cardiac arrest temperature ie significantly lower in the second cooling . (1) .
This demonstrates the acclimation effect previously reported
No significant differences xere found betxsen second and subsequent
ISOLATED PERFUSED HEART
242
100 90
Vol . 8, No . 5
BEATS PER MINUTE
BO 70 60 SO 40 30 20 )0 CA
.i.C
10
5
1
1~5
2~0
TEMPERATURE- °C
Mesa Heart Hate/Tupex~aturs Currea . ~ . - Hrst cooling, rithout noradrenaline . H . - Ssoond cooling, rithout not+aàrenaline : C . - Hrst cooling, rith noradrsnalins . D . - Third cooling, first and second rithout aoradrenaline third rith aoradrsaaline . C .l. - äsan cardiac arrest terpsnturs . oooliage . (3)
Sifecta of aooliaation and no :adreaalins ooabiaed . The fire hearts rhich had been aooliaated (in (2) abo~s) rere subjected
to a third ooôling and for this third cooling noradrenaline rae added to the perfnsate .
The lean Eate/Temperature cure is shorn as Curs D lig . 1 .
It can
Vol . 8, No . 5
1SaLATED PERFUSED HEART
24 3
bs seen that Cures D (noradrenaline with aoolirtioa) dose not differ iron o Curve C (aoradrenalins without accusation) between 20 and 14 C but below 14°C Cures D develops a sigoifioantly caller slope (P < 0.001) and also the cardiac arrest tesperature for Curve D ie significantly lover than that of Curve C .
The figures being 5.66°C (± 0.49) for Cures D and 10 .3 °C (± 0.23)
for Curve C .
Ths above resnlte shoe that the addition of noradrenaline to the psrfueate incxroased the heart rate throughout the cooling process.
llthough the Bate
Tenpsrature curve vas sowed to the left there vas no difference in slope between the control group (Ourve ~) and the noradrsnaline group.
The addition
of noradrsnaliae also resulted is the hearts continuing to beat to a tespsrature three degrees lover than the controls . These results are xhat night be ezpected fros a consideration of the actions of catscholaainss oa cardiac tissues .
(The actions of adrenaline and
noradrenaline oa the isolated heart are indietinguiehable although there are species differences is relative potency) .
Ia alsoet all respects the actions
of catecholaaiaea oppose the changes produced is cardiac f~aotion by cooling. Catecholaainea increase the rate of ispulee formation in the cardiac pacenaksr and all cardiac tissues capable of autosaticity (5) .
They also increase
the speed of iapulas conduction through all the cardiac tissues particularly the ~-V node (6) .
Catecholaaiase also increase the rates of contraction and
relazation of cardiac suacle (7) . The basic sechaaisms by rhich a tissue becomes acclimated to cold ere not understood but is the experiments described hers the process shoved itself ae a shift in the Bate~Tenperature sores to the left and a lowering of the teapsrature at xhich cardiac sweat occurred .
The reduction in cardiac
arrest tsapsrature produced by acclimation wan not significantly different to that produces by noradrenalias .
Vol . 8, No . 5
ISOLATED PERFUSED HEART
244
Hoxever, unlike the noradrenaline effect, the shlft to the left is the Rate/Temperature curve of the ncclimnted hearts xas accovpanied by a change of slops. fihen considering the role of catecholamines is cold aocllmation various sechaaisme have been proposed (8) .
Ths szperirents reported here suggest
that the process of cold acolimation produces a change in sensitivity of the heart to noradrsnaline as revealed by Curve D belox 14 o C .
Hoxsver,
noradrenaline does sot cause a change in slops of the Rate/Temperature curve xhsrsas acclimation doss .
The change is slope of Curve D belox 14oC suggests
that it might be amore correct to regard acclimation as a separate process xhich occurs both xith and xithout noradrsnaline. Conolnsions Noradrenaliae increases the rate of beating of the isolated heart at any given teaparature sad also causes a reduction of the teaperature at xhich aardiao arrest occurs .
It does not alter the elope of the Heart Rats/
Tsrpenturs curve. ~oolLation is a separate process xhioh increases the heart rate at lox t~peraturee during second and subsequent cooliage .
It decreases the elope
of the Heart Rate/Te~psrature curve significantly, and operates in both aoradrsnalias psrfused and control hearts . 8eferencee 1. 2.
N.Y . NOÜELL and D.C . fiHITS, Nature ~Londoa) 2~ 913 (1967) . 3.lI. HOEY~TH aad C .D . HOTiELL, ~dantation to the Snvimamsat . ed . ~.B . M11 p. 153 .
V. Pbysiol. 8oc. Washington D .C . (1964) .
3,
If .1[. BL~+w aad B.B . 1rI3HSH, ~. Phvsiol . 1~, fi30 (1954) .
4.
L1I, T~YLOH, Gf .D . HIIF1rINS$ and D .T . YOIING, J. ~DDl . Phvsiol. ~6, 95 (1961) .
Vol. 8, No. 5
LSOLATED PERFUSED HEART
Btfaraneaa
(coat .)
5.
s . CCR~80Er and 9 . if$IDltl~, H.1~. Ph~siol . ants . ~, ~j2 (1950 .
6.
H .H, SY,f,Ië and C .L . YHIHi>d$, J . Pbaraaaoi , 120, 137 (1957) .
7.
L .I . OOLDH>I80, ~a. J . Ph~aiol . ~, 92 (1958) .
8.
J . LEWC, ~ota ~aiol . 8oaad . ~, 8oPP1 " 183 (1961) .
245